/***************************************************************************/
/*                                                                         */
/*  afcjk.c                                                                */
/*                                                                         */
/*    Auto-fitter hinting routines for CJK script (body).                  */
/*                                                                         */
/*  Copyright 2006-2012 by                                                 */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/

/*
 *  The algorithm is based on akito's autohint patch, available here:
 *
 *  http://www.kde.gr.jp/~akito/patch/freetype2/
 *
 */

#include <ft2build.h>
#include FT_ADVANCES_H
#include FT_INTERNAL_DEBUG_H

#include "aftypes.h"
#include "aflatin.h"


#ifdef AF_CONFIG_OPTION_CJK

#undef AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT

#include "afcjk.h"
#include "aferrors.h"


#ifdef AF_CONFIG_OPTION_USE_WARPER
#include "afwarp.h"
#endif


/*************************************************************************/
/*                                                                       */
/* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
/* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
/* messages during execution.                                            */
/*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_afcjk


/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****              C J K   G L O B A L   M E T R I C S              *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/


/* Basically the Latin version with AF_CJKMetrics */
/* to replace AF_LatinMetrics.                    */

FT_LOCAL_DEF( void )
af_cjk_metrics_init_widths( AF_CJKMetrics metrics,
                            FT_Face face,
                            FT_ULong charcode )
{
    /* scan the array of segments in each direction */
    AF_GlyphHintsRec hints[1];


    af_glyph_hints_init( hints, face->memory );

    metrics->axis[ AF_DIMENSION_HORZ ].width_count = 0;
    metrics->axis[ AF_DIMENSION_VERT ].width_count = 0;

    {
        FT_Error error;
        FT_UInt glyph_index;
        int dim;
        AF_CJKMetricsRec dummy[1];
        AF_Scaler scaler = &dummy->root.scaler;


        glyph_index = FT_Get_Char_Index( face, charcode );
        if ( glyph_index == 0 )
        {
            goto Exit;
        }

        error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE);
        if ( error || face->glyph->outline.n_points <= 0 )
        {
            goto Exit;
        }

        FT_ZERO( dummy );

        dummy->units_per_em = metrics->units_per_em;

        scaler->x_scale = 0x10000L;
        scaler->y_scale = 0x10000L;
        scaler->x_delta = 0;
        scaler->y_delta = 0;

        scaler->face = face;
        scaler->render_mode = FT_RENDER_MODE_NORMAL;
        scaler->flags = 0;

        af_glyph_hints_rescale( hints, ( AF_ScriptMetrics ) dummy );

        error = af_glyph_hints_reload( hints, &face->glyph->outline );
        if ( error )
        {
            goto Exit;
        }

        for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
        {
            AF_CJKAxis axis = &metrics->axis[ dim ];
            AF_AxisHints axhints = &hints->axis[ dim ];
            AF_Segment seg, limit, link;
            FT_UInt num_widths = 0;


            error = af_latin_hints_compute_segments( hints, ( AF_Dimension ) dim );
            if ( error )
            {
                goto Exit;
            }

            af_latin_hints_link_segments( hints, ( AF_Dimension ) dim );

            seg = axhints->segments;
            limit = seg + axhints->num_segments;

            for ( ; seg < limit; seg++ )
            {
                link = seg->link;

                /* we only consider stem segments there! */
                if ( link && link->link == seg && link > seg )
                {
                    FT_Pos dist;


                    dist = seg->pos - link->pos;
                    if ( dist < 0 )
                    {
                        dist = -dist;
                    }

                    if ( num_widths < AF_CJK_MAX_WIDTHS )
                    {
                        axis->widths[ num_widths++ ].org = dist;
                    }
                }
            }

            af_sort_widths( num_widths, axis->widths );
            axis->width_count = num_widths;
        }

        Exit:
        for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
        {
            AF_CJKAxis axis = &metrics->axis[ dim ];
            FT_Pos stdw;


            stdw = ( axis->width_count > 0 ) ? axis->widths[ 0 ].org
                                             : AF_LATIN_CONSTANT( metrics, 50 );

            /* let's try 20% of the smallest width */
            axis->edge_distance_threshold = stdw / 5;
            axis->standard_width = stdw;
            axis->extra_light = 0;
        }
    }

    af_glyph_hints_done( hints );
}


#define AF_CJK_MAX_TEST_CHARACTERS  32


/* Each blue zone has two types of fill and unfill, this is, */
/* filling the entire glyph square or not.                   */

enum
{
    AF_CJK_BLUE_TYPE_FILL,
    AF_CJK_BLUE_TYPE_UNFILL,
    AF_CJK_BLUE_TYPE_MAX
};


/* Put some common and representative Han Ideographs characters here. */
static const FT_ULong af_cjk_hani_blue_chars[AF_CJK_BLUE_MAX]
[AF_CJK_BLUE_TYPE_MAX]
[AF_CJK_MAX_TEST_CHARACTERS] =
        {
                {
                        {
                                0x4ED6, 0x4EEC, 0x4F60, 0x4F86, 0x5011, 0x5230, 0x548C, 0x5730,
                                0x5BF9, 0x5C0D, 0x5C31, 0x5E2D, 0x6211, 0x65F6, 0x6642, 0x6703,
                                0x6765, 0x70BA, 0x80FD, 0x8230, 0x8AAA, 0x8BF4, 0x8FD9, 0x9019,
                                0x9F4A /* top fill */
                        },
                        {
                                0x519B, 0x540C, 0x5DF2, 0x613F, 0x65E2, 0x661F, 0x662F, 0x666F,
                                0x6C11, 0x7167, 0x73B0, 0x73FE, 0x7406, 0x7528, 0x7F6E, 0x8981,
                                0x8ECD, 0x90A3, 0x914D, 0x91CC, 0x958B, 0x96F7, 0x9732, 0x9762,
                                0x987E /* top unfill */
                        }
                },
                {
                        {
                                0x4E2A, 0x4E3A, 0x4EBA, 0x4ED6, 0x4EE5, 0x4EEC, 0x4F60, 0x4F86,
                                0x500B, 0x5011, 0x5230, 0x548C, 0x5927, 0x5BF9, 0x5C0D, 0x5C31,
                                0x6211, 0x65F6, 0x6642, 0x6709, 0x6765, 0x70BA, 0x8981, 0x8AAA,
                                0x8BF4 /* bottom fill */
                        },
                        {
                                0x4E3B, 0x4E9B, 0x56E0, 0x5B83, 0x60F3, 0x610F, 0x7406, 0x751F,
                                0x7576, 0x770B, 0x7740, 0x7F6E, 0x8005, 0x81EA, 0x8457, 0x88E1,
                                0x8FC7, 0x8FD8, 0x8FDB, 0x9032, 0x904E, 0x9053, 0x9084, 0x91CC,
                                0x9762 /* bottom unfill */
                        }
                },
#ifndef AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT
                {{ 0x0000 }, { 0x0000 }},
                {{ 0x0000 }, { 0x0000 }}
#else
        {
          {
            0x4E9B, 0x4EEC, 0x4F60, 0x4F86, 0x5011, 0x5230, 0x548C, 0x5730,
            0x5979, 0x5C06, 0x5C07, 0x5C31, 0x5E74, 0x5F97, 0x60C5, 0x6700,
            0x6837, 0x6A23, 0x7406, 0x80FD, 0x8AAA, 0x8BF4, 0x8FD9, 0x9019,
            0x901A /* left fill */
          },
          {
            0x5373, 0x5417, 0x5427, 0x542C, 0x5462, 0x54C1, 0x54CD, 0x55CE,
            0x5E08, 0x5E2B, 0x6536, 0x65AD, 0x65B7, 0x660E, 0x773C, 0x9593,
            0x95F4, 0x9645, 0x9648, 0x9650, 0x9664, 0x9673, 0x968F, 0x969B,
            0x96A8 /* left unfill */
          }
        },
        {
          {
            0x4E8B, 0x524D, 0x5B78, 0x5C06, 0x5C07, 0x60C5, 0x60F3, 0x6216,
            0x653F, 0x65AF, 0x65B0, 0x6837, 0x6A23, 0x6C11, 0x6C92, 0x6CA1,
            0x7136, 0x7279, 0x73B0, 0x73FE, 0x7403, 0x7B2C, 0x7D93, 0x8C01,
            0x8D77 /* right fill */
          },
          {
            0x4F8B, 0x5225, 0x522B, 0x5236, 0x52A8, 0x52D5, 0x5417, 0x55CE,
            0x589E, 0x6307, 0x660E, 0x671D, 0x671F, 0x6784, 0x7269, 0x786E,
            0x79CD, 0x8ABF, 0x8C03, 0x8CBB, 0x8D39, 0x90A3, 0x90FD, 0x9593,
            0x95F4 /* right unfill */
          }
        }
#endif /* AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT */
        };


/* Calculate blue zones for all the CJK_BLUE_XXX's. */

static void
af_cjk_metrics_init_blues( AF_CJKMetrics metrics,
                           FT_Face face,
                           const FT_ULong blue_chars
                           [AF_CJK_BLUE_MAX]
                           [AF_CJK_BLUE_TYPE_MAX]
                           [AF_CJK_MAX_TEST_CHARACTERS] )
{
    FT_Pos fills[AF_CJK_MAX_TEST_CHARACTERS];
    FT_Pos flats[AF_CJK_MAX_TEST_CHARACTERS];

    FT_Int num_fills;
    FT_Int num_flats;

    FT_Int bb;
    AF_CJKBlue blue;
    FT_Error error;
    AF_CJKAxis axis;
    FT_GlyphSlot glyph = face->glyph;

#ifdef FT_DEBUG_LEVEL_TRACE
    FT_String*  cjk_blue_name[AF_CJK_BLUE_MAX] = {
      (FT_String*)"top",
      (FT_String*)"bottom",
      (FT_String*)"left",
      (FT_String*)"right"
    };
    FT_String*  cjk_blue_type_name[AF_CJK_BLUE_TYPE_MAX] = {
      (FT_String*)"filled",
      (FT_String*)"unfilled"
    };
#endif


    /* We compute the blues simply by loading each character from the */
    /* `blue_chars[blues]' string, then computing its extreme points  */
    /* (depending blue zone type etc.).                               */

    FT_TRACE5(( "cjk blue zones computation\n" ));
    FT_TRACE5(( "------------------------------------------------\n" ));

    for ( bb = 0; bb < AF_CJK_BLUE_MAX; bb++ )
    {
        FT_Int fill_type;
        FT_Pos *blue_ref;
        FT_Pos *blue_shoot;


        num_fills = 0;
        num_flats = 0;

        for ( fill_type = 0; fill_type < AF_CJK_BLUE_TYPE_MAX; fill_type++ )
        {
            const FT_ULong *p = blue_chars[ bb ][ fill_type ];
            const FT_ULong *limit = p + AF_CJK_MAX_TEST_CHARACTERS;
            FT_Bool fill = FT_BOOL(
                    fill_type == AF_CJK_BLUE_TYPE_FILL );


            FT_TRACE5(( "cjk blue %s/%s\n", cjk_blue_name[ bb ],
                    cjk_blue_type_name[ fill_type ] ));


            for ( ; p < limit && *p; p++ )
            {
                FT_UInt glyph_index;
                FT_Pos best_pos; /* same as points.y */
                FT_Int best_point;
                FT_Vector *points;


                FT_TRACE5(( "  U+%lX...", *p ));

                /* load the character in the face -- skip unknown or empty ones */
                glyph_index = FT_Get_Char_Index( face, *p );
                if ( glyph_index == 0 )
                {
                    FT_TRACE5(( "unavailable\n" ));
                    continue;
                }

                error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE);
                if ( error || glyph->outline.n_points <= 0 )
                {
                    FT_TRACE5(( "no outline\n" ));
                    continue;
                }

                /* now compute min or max point indices and coordinates */
                points = glyph->outline.points;
                best_point = -1;
                best_pos = 0;  /* make compiler happy */

                {
                    FT_Int nn;
                    FT_Int first = 0;
                    FT_Int last = -1;


                    for ( nn = 0;
                          nn < glyph->outline.n_contours;
                          first = last + 1, nn++ )
                    {
                        FT_Int pp;


                        last = glyph->outline.contours[ nn ];

                        /* Avoid single-point contours since they are never       */
                        /* rasterized.  In some fonts, they correspond to mark    */
                        /* attachment points which are way outside of the glyph's */
                        /* real outline.                                          */
                        if ( last <= first )
                        {
                            continue;
                        }

                        switch ( bb )
                        {
                            case AF_CJK_BLUE_TOP:
                                for ( pp = first; pp <= last; pp++ )
                                {
                                    if ( best_point < 0 || points[ pp ].y > best_pos )
                                    {
                                        best_point = pp;
                                        best_pos = points[ pp ].y;
                                    }
                                }
                                break;

                            case AF_CJK_BLUE_BOTTOM:
                                for ( pp = first; pp <= last; pp++ )
                                {
                                    if ( best_point < 0 || points[ pp ].y < best_pos )
                                    {
                                        best_point = pp;
                                        best_pos = points[ pp ].y;
                                    }
                                }
                                break;

                            case AF_CJK_BLUE_LEFT:
                                for ( pp = first; pp <= last; pp++ )
                                {
                                    if ( best_point < 0 || points[ pp ].x < best_pos )
                                    {
                                        best_point = pp;
                                        best_pos = points[ pp ].x;
                                    }
                                }
                                break;

                            case AF_CJK_BLUE_RIGHT:
                                for ( pp = first; pp <= last; pp++ )
                                {
                                    if ( best_point < 0 || points[ pp ].x > best_pos )
                                    {
                                        best_point = pp;
                                        best_pos = points[ pp ].x;
                                    }
                                }
                                break;

                            default:;
                        }
                    }
                    FT_TRACE5(( "best_pos=%5ld\n", best_pos ));
                }

                if ( fill )
                {
                    fills[ num_fills++ ] = best_pos;
                }
                else
                {
                    flats[ num_flats++ ] = best_pos;
                }
            }
        }

        if ( num_flats == 0 && num_fills == 0 )
        {
            /*
             *  we couldn't find a single glyph to compute this blue zone,
             *  we will simply ignore it then
             */
            FT_TRACE5(( "empty\n" ));
            continue;
        }

        /* we have computed the contents of the `fill' and `flats' tables, */
        /* now determine the reference position of the blue --             */
        /* we simply take the median value after a simple sort             */
        af_sort_pos( num_flats, flats );
        af_sort_pos( num_fills, fills );

        if ( AF_CJK_BLUE_TOP == bb || AF_CJK_BLUE_BOTTOM == bb )
        {
            axis = &metrics->axis[ AF_DIMENSION_VERT ];
        }
        else
        {
            axis = &metrics->axis[ AF_DIMENSION_HORZ ];
        }

        blue = &axis->blues[ axis->blue_count ];
        blue_ref = &blue->ref.org;
        blue_shoot = &blue->shoot.org;

        axis->blue_count++;
        if ( num_flats == 0 )
        {
            *blue_ref = fills[ num_fills / 2 ];
            *blue_shoot = fills[ num_fills / 2 ];
        }
        else if ( num_fills == 0 )
        {
            *blue_ref = flats[ num_flats / 2 ];
            *blue_shoot = flats[ num_flats / 2 ];
        }
        else
        {
            *blue_ref = fills[ num_fills / 2 ];
            *blue_shoot = flats[ num_flats / 2 ];
        }

        /* make sure blue_ref >= blue_shoot for top/right or */
        /* vice versa for bottom/left                        */
        if ( *blue_shoot != *blue_ref )
        {
            FT_Pos ref = *blue_ref;
            FT_Pos shoot = *blue_shoot;
            FT_Bool under_ref = FT_BOOL( shoot < ref );


            if (( AF_CJK_BLUE_TOP == bb || AF_CJK_BLUE_RIGHT == bb ) ^ under_ref )
            {
                *blue_shoot = *blue_ref = ( shoot + ref ) / 2;
            }
        }

        blue->flags = 0;
        if ( AF_CJK_BLUE_TOP == bb )
        {
            blue->flags |= AF_CJK_BLUE_IS_TOP;
        }
        else if ( AF_CJK_BLUE_RIGHT == bb )
        {
            blue->flags |= AF_CJK_BLUE_IS_RIGHT;
        }

        FT_TRACE5(( "-- cjk %s bluezone ref = %ld shoot = %ld\n",
                cjk_blue_name[ bb ], *blue_ref, *blue_shoot ));
    }

    return;
}


/* Basically the Latin version with type AF_CJKMetrics for metrics. */
FT_LOCAL_DEF( void )
af_cjk_metrics_check_digits( AF_CJKMetrics metrics,
                             FT_Face face )
{
    FT_UInt i;
    FT_Bool started = 0, same_width = 1;
    FT_Fixed advance, old_advance = 0;


    /* check whether all ASCII digits have the same advance width; */
    /* digit `0' is 0x30 in all supported charmaps                 */
    for ( i = 0x30; i <= 0x39; i++ )
    {
        FT_UInt glyph_index;


        glyph_index = FT_Get_Char_Index( face, i );
        if ( glyph_index == 0 )
        {
            continue;
        }

        if ( FT_Get_Advance( face, glyph_index,
                             FT_LOAD_NO_SCALE |
                             FT_LOAD_NO_HINTING |
                             FT_LOAD_IGNORE_TRANSFORM,
                             &advance ))
        {
            continue;
        }

        if ( started )
        {
            if ( advance != old_advance )
            {
                same_width = 0;
                break;
            }
        }
        else
        {
            old_advance = advance;
            started = 1;
        }
    }

    metrics->root.digits_have_same_width = same_width;
}


FT_LOCAL_DEF( FT_Error )
af_cjk_metrics_init( AF_CJKMetrics metrics,
                     FT_Face face )
{
    FT_CharMap oldmap = face->charmap;


    metrics->units_per_em = face->units_per_EM;

    if ( FT_Select_Charmap( face, FT_ENCODING_UNICODE ))
    {
        face->charmap = NULL;
    }
    else
    {
        af_cjk_metrics_init_widths( metrics, face, 0x7530 );
        af_cjk_metrics_init_blues( metrics, face, af_cjk_hani_blue_chars );
        af_cjk_metrics_check_digits( metrics, face );
    }

    FT_Set_Charmap( face, oldmap );

    return AF_Err_Ok;
}


static void
af_cjk_metrics_scale_dim( AF_CJKMetrics metrics,
                          AF_Scaler scaler,
                          AF_Dimension dim )
{
    FT_Fixed scale;
    FT_Pos delta;
    AF_CJKAxis axis;
    FT_UInt nn;


    axis = &metrics->axis[ dim ];

    if ( dim == AF_DIMENSION_HORZ )
    {
        scale = scaler->x_scale;
        delta = scaler->x_delta;
    }
    else
    {
        scale = scaler->y_scale;
        delta = scaler->y_delta;
    }

    if ( axis->org_scale == scale && axis->org_delta == delta )
    {
        return;
    }

    axis->org_scale = scale;
    axis->org_delta = delta;

    axis->scale = scale;
    axis->delta = delta;

    /* scale the blue zones */
    for ( nn = 0; nn < axis->blue_count; nn++ )
    {
        AF_CJKBlue blue = &axis->blues[ nn ];
        FT_Pos dist;


        blue->ref.cur = FT_MulFix( blue->ref.org, scale ) + delta;
        blue->ref.fit = blue->ref.cur;
        blue->shoot.cur = FT_MulFix( blue->shoot.org, scale ) + delta;
        blue->shoot.fit = blue->shoot.cur;
        blue->flags &= ~AF_CJK_BLUE_ACTIVE;

        /* a blue zone is only active if it is less than 3/4 pixels tall */
        dist = FT_MulFix( blue->ref.org - blue->shoot.org, scale );
        if ( dist <= 48 && dist >= -48 )
        {
            FT_Pos delta1, delta2;


            blue->ref.fit = FT_PIX_ROUND( blue->ref.cur );

            /* shoot is under shoot for cjk */
            delta1 = FT_DivFix( blue->ref.fit, scale ) - blue->shoot.org;
            delta2 = delta1;
            if ( delta1 < 0 )
            {
                delta2 = -delta2;
            }

            delta2 = FT_MulFix( delta2, scale );

            FT_TRACE5(( "delta: %d", delta1 ));
            if ( delta2 < 32 )
            {
                delta2 = 0;
            }
#if 0
                else if ( delta2 < 64 )
                  delta2 = 32 + ( ( ( delta2 - 32 ) + 16 ) & ~31 );
#endif
            else
            {
                delta2 = FT_PIX_ROUND( delta2 );
            }
            FT_TRACE5(( "/%d\n", delta2 ));

            if ( delta1 < 0 )
            {
                delta2 = -delta2;
            }

            blue->shoot.fit = blue->ref.fit - delta2;

            FT_TRACE5(( ">> active cjk blue zone %c%d[%ld/%ld]: "
                        "ref: cur=%.2f fit=%.2f shoot: cur=%.2f fit=%.2f\n",
                    ( dim == AF_DIMENSION_HORZ ) ? 'H' : 'V',
                    nn, blue->ref.org, blue->shoot.org,
                    blue->ref.cur / 64.0, blue->ref.fit / 64.0,
                    blue->shoot.cur / 64.0, blue->shoot.fit / 64.0 ));

            blue->flags |= AF_CJK_BLUE_ACTIVE;
        }
    }
}


FT_LOCAL_DEF( void )
af_cjk_metrics_scale( AF_CJKMetrics metrics,
                      AF_Scaler scaler )
{
    metrics->root.scaler = *scaler;

    af_cjk_metrics_scale_dim( metrics, scaler, AF_DIMENSION_HORZ );
    af_cjk_metrics_scale_dim( metrics, scaler, AF_DIMENSION_VERT );
}


/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****              C J K   G L Y P H   A N A L Y S I S              *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/

static FT_Error
af_cjk_hints_compute_segments( AF_GlyphHints hints,
                               AF_Dimension dim )
{
    AF_AxisHints axis = &hints->axis[ dim ];
    AF_Segment segments = axis->segments;
    AF_Segment segment_limit = segments + axis->num_segments;
    FT_Error error;
    AF_Segment seg;


    error = af_latin_hints_compute_segments( hints, dim );
    if ( error )
    {
        return error;
    }

    /* a segment is round if it doesn't have successive */
    /* on-curve points.                                 */
    for ( seg = segments; seg < segment_limit; seg++ )
    {
        AF_Point pt = seg->first;
        AF_Point last = seg->last;
        AF_Flags f0 = ( AF_Flags ) ( pt->flags & AF_FLAG_CONTROL );
        AF_Flags f1;


        seg->flags &= ~AF_EDGE_ROUND;

        for ( ; pt != last; f0 = f1 )
        {
            pt = pt->next;
            f1 = ( AF_Flags ) ( pt->flags & AF_FLAG_CONTROL );

            if ( !f0 && !f1 )
            {
                break;
            }

            if ( pt == last )
            {
                seg->flags |= AF_EDGE_ROUND;
            }
        }
    }

    return AF_Err_Ok;
}


static void
af_cjk_hints_link_segments( AF_GlyphHints hints,
                            AF_Dimension dim )
{
    AF_AxisHints axis = &hints->axis[ dim ];
    AF_Segment segments = axis->segments;
    AF_Segment segment_limit = segments + axis->num_segments;
    AF_Direction major_dir = axis->major_dir;
    AF_Segment seg1, seg2;
    FT_Pos len_threshold;
    FT_Pos dist_threshold;


    len_threshold = AF_LATIN_CONSTANT( hints->metrics, 8 );

    dist_threshold = ( dim == AF_DIMENSION_HORZ ) ? hints->x_scale
                                                  : hints->y_scale;
    dist_threshold = FT_DivFix( 64 * 3, dist_threshold );

    /* now compare each segment to the others */
    for ( seg1 = segments; seg1 < segment_limit; seg1++ )
    {
        /* the fake segments are for metrics hinting only */
        if ( seg1->first == seg1->last )
        {
            continue;
        }

        if ( seg1->dir != major_dir )
        {
            continue;
        }

        for ( seg2 = segments; seg2 < segment_limit; seg2++ )
        {
            if ( seg2 != seg1 && seg1->dir + seg2->dir == 0 )
            {
                FT_Pos dist = seg2->pos - seg1->pos;


                if ( dist < 0 )
                {
                    continue;
                }

                {
                    FT_Pos min = seg1->min_coord;
                    FT_Pos max = seg1->max_coord;
                    FT_Pos len;


                    if ( min < seg2->min_coord )
                    {
                        min = seg2->min_coord;
                    }

                    if ( max > seg2->max_coord )
                    {
                        max = seg2->max_coord;
                    }

                    len = max - min;
                    if ( len >= len_threshold )
                    {
                        if ( dist * 8 < seg1->score * 9 &&
                             ( dist * 8 < seg1->score * 7 || seg1->len < len ))
                        {
                            seg1->score = dist;
                            seg1->len = len;
                            seg1->link = seg2;
                        }

                        if ( dist * 8 < seg2->score * 9 &&
                             ( dist * 8 < seg2->score * 7 || seg2->len < len ))
                        {
                            seg2->score = dist;
                            seg2->len = len;
                            seg2->link = seg1;
                        }
                    }
                }
            }
        }
    }

    /*
     *  now compute the `serif' segments
     *
     *  In Hanzi, some strokes are wider on one or both of the ends.
     *  We either identify the stems on the ends as serifs or remove
     *  the linkage, depending on the length of the stems.
     *
     */

    {
        AF_Segment link1, link2;


        for ( seg1 = segments; seg1 < segment_limit; seg1++ )
        {
            link1 = seg1->link;
            if ( !link1 || link1->link != seg1 || link1->pos <= seg1->pos )
            {
                continue;
            }

            if ( seg1->score >= dist_threshold )
            {
                continue;
            }

            for ( seg2 = segments; seg2 < segment_limit; seg2++ )
            {
                if ( seg2->pos > seg1->pos || seg1 == seg2 )
                {
                    continue;
                }

                link2 = seg2->link;
                if ( !link2 || link2->link != seg2 || link2->pos < link1->pos )
                {
                    continue;
                }

                if ( seg1->pos == seg2->pos && link1->pos == link2->pos )
                {
                    continue;
                }

                if ( seg2->score <= seg1->score || seg1->score * 4 <= seg2->score )
                {
                    continue;
                }

                /* seg2 < seg1 < link1 < link2 */

                if ( seg1->len >= seg2->len * 3 )
                {
                    AF_Segment seg;


                    for ( seg = segments; seg < segment_limit; seg++ )
                    {
                        AF_Segment link = seg->link;


                        if ( link == seg2 )
                        {
                            seg->link = 0;
                            seg->serif = link1;
                        }
                        else if ( link == link2 )
                        {
                            seg->link = 0;
                            seg->serif = seg1;
                        }
                    }
                }
                else
                {
                    seg1->link = link1->link = 0;

                    break;
                }
            }
        }
    }

    for ( seg1 = segments; seg1 < segment_limit; seg1++ )
    {
        seg2 = seg1->link;

        if ( seg2 )
        {
            seg2->num_linked++;
            if ( seg2->link != seg1 )
            {
                seg1->link = 0;

                if ( seg2->score < dist_threshold || seg1->score < seg2->score * 4 )
                {
                    seg1->serif = seg2->link;
                }
                else
                {
                    seg2->num_linked--;
                }
            }
        }
    }
}


static FT_Error
af_cjk_hints_compute_edges( AF_GlyphHints hints,
                            AF_Dimension dim )
{
    AF_AxisHints axis = &hints->axis[ dim ];
    FT_Error error = AF_Err_Ok;
    FT_Memory memory = hints->memory;
    AF_CJKAxis laxis = &(( AF_CJKMetrics ) hints->metrics )->axis[ dim ];

    AF_Segment segments = axis->segments;
    AF_Segment segment_limit = segments + axis->num_segments;
    AF_Segment seg;

    FT_Fixed scale;
    FT_Pos edge_distance_threshold;


    axis->num_edges = 0;

    scale = ( dim == AF_DIMENSION_HORZ ) ? hints->x_scale
                                         : hints->y_scale;

    /*********************************************************************/
    /*                                                                   */
    /* We begin by generating a sorted table of edges for the current    */
    /* direction.  To do so, we simply scan each segment and try to find */
    /* an edge in our table that corresponds to its position.            */
    /*                                                                   */
    /* If no edge is found, we create and insert a new edge in the       */
    /* sorted table.  Otherwise, we simply add the segment to the edge's */
    /* list which is then processed in the second step to compute the    */
    /* edge's properties.                                                */
    /*                                                                   */
    /* Note that the edges table is sorted along the segment/edge        */
    /* position.                                                         */
    /*                                                                   */
    /*********************************************************************/

    edge_distance_threshold = FT_MulFix( laxis->edge_distance_threshold,
                                         scale );
    if ( edge_distance_threshold > 64 / 4 )
    {
        edge_distance_threshold = FT_DivFix( 64 / 4, scale );
    }
    else
    {
        edge_distance_threshold = laxis->edge_distance_threshold;
    }

    for ( seg = segments; seg < segment_limit; seg++ )
    {
        AF_Edge found = 0;
        FT_Pos best = 0xFFFFU;
        FT_Int ee;


        /* look for an edge corresponding to the segment */
        for ( ee = 0; ee < axis->num_edges; ee++ )
        {
            AF_Edge edge = axis->edges + ee;
            FT_Pos dist;


            if ( edge->dir != seg->dir )
            {
                continue;
            }

            dist = seg->pos - edge->fpos;
            if ( dist < 0 )
            {
                dist = -dist;
            }

            if ( dist < edge_distance_threshold && dist < best )
            {
                AF_Segment link = seg->link;


                /* check whether all linked segments of the candidate edge */
                /* can make a single edge.                                 */
                if ( link )
                {
                    AF_Segment seg1 = edge->first;
                    AF_Segment link1;
                    FT_Pos dist2 = 0;


                    do
                    {
                        link1 = seg1->link;
                        if ( link1 )
                        {
                            dist2 = AF_SEGMENT_DIST( link, link1 );
                            if ( dist2 >= edge_distance_threshold )
                            {
                                break;
                            }
                        }

                    }
                    while (( seg1 = seg1->edge_next ) != edge->first );

                    if ( dist2 >= edge_distance_threshold )
                    {
                        continue;
                    }
                }

                best = dist;
                found = edge;
            }
        }

        if ( !found )
        {
            AF_Edge edge;


            /* insert a new edge in the list and */
            /* sort according to the position    */
            error = af_axis_hints_new_edge( axis, seg->pos,
                                            ( AF_Direction ) seg->dir,
                                            memory, &edge );
            if ( error )
            {
                goto Exit;
            }

            /* add the segment to the new edge's list */
            FT_ZERO( edge );

            edge->first = seg;
            edge->last = seg;
            edge->fpos = seg->pos;
            edge->opos = edge->pos = FT_MulFix( seg->pos, scale );
            seg->edge_next = seg;
            edge->dir = seg->dir;
        }
        else
        {
            /* if an edge was found, simply add the segment to the edge's */
            /* list                                                       */
            seg->edge_next = found->first;
            found->last->edge_next = seg;
            found->last = seg;
        }
    }

    /*********************************************************************/
    /*                                                                   */
    /* Good, we now compute each edge's properties according to segments */
    /* found on its position.  Basically, these are as follows.          */
    /*                                                                   */
    /*  - edge's main direction                                          */
    /*  - stem edge, serif edge or both (which defaults to stem then)    */
    /*  - rounded edge, straight or both (which defaults to straight)    */
    /*  - link for edge                                                  */
    /*                                                                   */
    /*********************************************************************/

    /* first of all, set the `edge' field in each segment -- this is     */
    /* required in order to compute edge links                           */
    /*                                                                   */
    /* Note that removing this loop and setting the `edge' field of each */
    /* segment directly in the code above slows down execution speed for */
    /* some reasons on platforms like the Sun.                           */

    {
        AF_Edge edges = axis->edges;
        AF_Edge edge_limit = edges + axis->num_edges;
        AF_Edge edge;


        for ( edge = edges; edge < edge_limit; edge++ )
        {
            seg = edge->first;
            if ( seg )
            {
                do
                {
                    seg->edge = edge;
                    seg = seg->edge_next;

                }
                while ( seg != edge->first );
            }
        }

        /* now compute each edge properties */
        for ( edge = edges; edge < edge_limit; edge++ )
        {
            FT_Int is_round = 0;  /* does it contain round segments?    */
            FT_Int is_straight = 0;  /* does it contain straight segments? */


            seg = edge->first;

            do
            {
                FT_Bool is_serif;


                /* check for roundness of segment */
                if ( seg->flags & AF_EDGE_ROUND )
                {
                    is_round++;
                }
                else
                {
                    is_straight++;
                }

                /* check for links -- if seg->serif is set, then seg->link must */
                /* be ignored                                                   */
                is_serif = ( FT_Bool ) ( seg->serif && seg->serif->edge != edge );

                if ( seg->link || is_serif )
                {
                    AF_Edge edge2;
                    AF_Segment seg2;


                    edge2 = edge->link;
                    seg2 = seg->link;

                    if ( is_serif )
                    {
                        seg2 = seg->serif;
                        edge2 = edge->serif;
                    }

                    if ( edge2 )
                    {
                        FT_Pos edge_delta;
                        FT_Pos seg_delta;


                        edge_delta = edge->fpos - edge2->fpos;
                        if ( edge_delta < 0 )
                        {
                            edge_delta = -edge_delta;
                        }

                        seg_delta = AF_SEGMENT_DIST( seg, seg2 );

                        if ( seg_delta < edge_delta )
                        {
                            edge2 = seg2->edge;
                        }
                    }
                    else
                    {
                        edge2 = seg2->edge;
                    }

                    if ( is_serif )
                    {
                        edge->serif = edge2;
                        edge2->flags |= AF_EDGE_SERIF;
                    }
                    else
                    {
                        edge->link = edge2;
                    }
                }

                seg = seg->edge_next;

            }
            while ( seg != edge->first );

            /* set the round/straight flags */
            edge->flags = AF_EDGE_NORMAL;

            if ( is_round > 0 && is_round >= is_straight )
            {
                edge->flags |= AF_EDGE_ROUND;
            }

            /* get rid of serifs if link is set                 */
            /* XXX: This gets rid of many unpleasant artefacts! */
            /*      Example: the `c' in cour.pfa at size 13     */

            if ( edge->serif && edge->link )
            {
                edge->serif = 0;
            }
        }
    }

    Exit:
    return error;
}


static FT_Error
af_cjk_hints_detect_features( AF_GlyphHints hints,
                              AF_Dimension dim )
{
    FT_Error error;


    error = af_cjk_hints_compute_segments( hints, dim );
    if ( !error )
    {
        af_cjk_hints_link_segments( hints, dim );

        error = af_cjk_hints_compute_edges( hints, dim );
    }
    return error;
}


FT_LOCAL_DEF( void )
af_cjk_hints_compute_blue_edges( AF_GlyphHints hints,
                                 AF_CJKMetrics metrics,
                                 AF_Dimension dim )
{
    AF_AxisHints axis = &hints->axis[ dim ];
    AF_Edge edge = axis->edges;
    AF_Edge edge_limit = edge + axis->num_edges;
    AF_CJKAxis cjk = &metrics->axis[ dim ];
    FT_Fixed scale = cjk->scale;
    FT_Pos best_dist0;  /* initial threshold */


    /* compute the initial threshold as a fraction of the EM size */
    best_dist0 = FT_MulFix( metrics->units_per_em / 40, scale );

    if ( best_dist0 > 64 / 2 )
    { /* maximum 1/2 pixel */
        best_dist0 = 64 / 2;
    }

    /* compute which blue zones are active, i.e. have their scaled */
    /* size < 3/4 pixels                                           */

    /* If the distant between an edge and a blue zone is shorter than */
    /* best_dist0, set the blue zone for the edge.  Then search for   */
    /* the blue zone with the smallest best_dist to the edge.         */

    for ( ; edge < edge_limit; edge++ )
    {
        FT_UInt bb;
        AF_Width best_blue = NULL;
        FT_Pos best_dist = best_dist0;


        for ( bb = 0; bb < cjk->blue_count; bb++ )
        {
            AF_CJKBlue blue = cjk->blues + bb;
            FT_Bool is_top_right_blue, is_major_dir;


            /* skip inactive blue zones (i.e., those that are too small) */
            if ( !( blue->flags & AF_CJK_BLUE_ACTIVE ))
            {
                continue;
            }

            /* if it is a top zone, check for right edges -- if it is a bottom */
            /* zone, check for left edges                                      */
            /*                                                                 */
            /* of course, that's for TrueType                                  */
            is_top_right_blue =
                    FT_BOOL((( blue->flags & AF_CJK_BLUE_IS_TOP ) != 0 ) ||
                            (( blue->flags & AF_CJK_BLUE_IS_RIGHT ) != 0 ));
            is_major_dir = FT_BOOL( edge->dir == axis->major_dir );

            /* if it is a top zone, the edge must be against the major    */
            /* direction; if it is a bottom zone, it must be in the major */
            /* direction                                                  */
            if ( is_top_right_blue ^ is_major_dir )
            {
                FT_Pos dist;
                AF_Width compare;


                /* Compare the edge to the closest blue zone type */
                if ( FT_ABS( edge->fpos - blue->ref.org ) >
                     FT_ABS( edge->fpos - blue->shoot.org ))
                {
                    compare = &blue->shoot;
                }
                else
                {
                    compare = &blue->ref;
                }

                dist = edge->fpos - compare->org;
                if ( dist < 0 )
                {
                    dist = -dist;
                }

                dist = FT_MulFix( dist, scale );
                if ( dist < best_dist )
                {
                    best_dist = dist;
                    best_blue = compare;
                }
            }
        }

        if ( best_blue )
        {
            edge->blue_edge = best_blue;
        }
    }
}


FT_LOCAL_DEF( FT_Error )
af_cjk_hints_init( AF_GlyphHints hints,
                   AF_CJKMetrics metrics )
{
    FT_Render_Mode mode;
    FT_UInt32 scaler_flags, other_flags;


    af_glyph_hints_rescale( hints, ( AF_ScriptMetrics ) metrics );

    /*
     *  correct x_scale and y_scale when needed, since they may have
     *  been modified af_cjk_scale_dim above
     */
    hints->x_scale = metrics->axis[ AF_DIMENSION_HORZ ].scale;
    hints->x_delta = metrics->axis[ AF_DIMENSION_HORZ ].delta;
    hints->y_scale = metrics->axis[ AF_DIMENSION_VERT ].scale;
    hints->y_delta = metrics->axis[ AF_DIMENSION_VERT ].delta;

    /* compute flags depending on render mode, etc. */
    mode = metrics->root.scaler.render_mode;

#ifdef AF_CONFIG_OPTION_USE_WARPER
    if ( mode == FT_RENDER_MODE_LCD || mode == FT_RENDER_MODE_LCD_V )
      metrics->root.scaler.render_mode = mode = FT_RENDER_MODE_NORMAL;
#endif

    scaler_flags = hints->scaler_flags;
    other_flags = 0;

    /*
     *  We snap the width of vertical stems for the monochrome and
     *  horizontal LCD rendering targets only.
     */
    if ( mode == FT_RENDER_MODE_MONO || mode == FT_RENDER_MODE_LCD )
    {
        other_flags |= AF_LATIN_HINTS_HORZ_SNAP;
    }

    /*
     *  We snap the width of horizontal stems for the monochrome and
     *  vertical LCD rendering targets only.
     */
    if ( mode == FT_RENDER_MODE_MONO || mode == FT_RENDER_MODE_LCD_V )
    {
        other_flags |= AF_LATIN_HINTS_VERT_SNAP;
    }

    /*
     *  We adjust stems to full pixels only if we don't use the `light' mode.
     */
    if ( mode != FT_RENDER_MODE_LIGHT )
    {
        other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
    }

    if ( mode == FT_RENDER_MODE_MONO )
    {
        other_flags |= AF_LATIN_HINTS_MONO;
    }

    scaler_flags |= AF_SCALER_FLAG_NO_ADVANCE;

    hints->scaler_flags = scaler_flags;
    hints->other_flags = other_flags;

    return 0;
}


/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****          C J K   G L Y P H   G R I D - F I T T I N G          *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/

/* snap a given width in scaled coordinates to one of the */
/* current standard widths                                */

static FT_Pos
af_cjk_snap_width( AF_Width widths,
                   FT_Int count,
                   FT_Pos width )
{
    int n;
    FT_Pos best = 64 + 32 + 2;
    FT_Pos reference = width;
    FT_Pos scaled;


    for ( n = 0; n < count; n++ )
    {
        FT_Pos w;
        FT_Pos dist;


        w = widths[ n ].cur;
        dist = width - w;
        if ( dist < 0 )
        {
            dist = -dist;
        }
        if ( dist < best )
        {
            best = dist;
            reference = w;
        }
    }

    scaled = FT_PIX_ROUND( reference );

    if ( width >= reference )
    {
        if ( width < scaled + 48 )
        {
            width = reference;
        }
    }
    else
    {
        if ( width > scaled - 48 )
        {
            width = reference;
        }
    }

    return width;
}


/* compute the snapped width of a given stem */

static FT_Pos
af_cjk_compute_stem_width( AF_GlyphHints hints,
                           AF_Dimension dim,
                           FT_Pos width,
                           AF_Edge_Flags base_flags,
                           AF_Edge_Flags stem_flags )
{
    AF_CJKMetrics metrics = ( AF_CJKMetrics ) hints->metrics;
    AF_CJKAxis axis = &metrics->axis[ dim ];
    FT_Pos dist = width;
    FT_Int sign = 0;
    FT_Bool vertical = FT_BOOL( dim == AF_DIMENSION_VERT );

    FT_UNUSED( base_flags );
    FT_UNUSED( stem_flags );


    if ( !AF_LATIN_HINTS_DO_STEM_ADJUST( hints ))
    {
        return width;
    }

    if ( dist < 0 )
    {
        dist = -width;
        sign = 1;
    }

    if (( vertical && !AF_LATIN_HINTS_DO_VERT_SNAP( hints )) ||
        ( !vertical && !AF_LATIN_HINTS_DO_HORZ_SNAP( hints )))
    {
        /* smooth hinting process: very lightly quantize the stem width */

        if ( axis->width_count > 0 )
        {
            if ( FT_ABS( dist - axis->widths[ 0 ].cur ) < 40 )
            {
                dist = axis->widths[ 0 ].cur;
                if ( dist < 48 )
                {
                    dist = 48;
                }

                goto Done_Width;
            }
        }

        if ( dist < 54 )
        {
            dist += ( 54 - dist ) / 2;
        }
        else if ( dist < 3 * 64 )
        {
            FT_Pos delta;


            delta = dist & 63;
            dist &= -64;

            if ( delta < 10 )
            {
                dist += delta;
            }
            else if ( delta < 22 )
            {
                dist += 10;
            }
            else if ( delta < 42 )
            {
                dist += delta;
            }
            else if ( delta < 54 )
            {
                dist += 54;
            }
            else
            {
                dist += delta;
            }
        }
    }
    else
    {
        /* strong hinting process: snap the stem width to integer pixels */

        dist = af_cjk_snap_width( axis->widths, axis->width_count, dist );

        if ( vertical )
        {
            /* in the case of vertical hinting, always round */
            /* the stem heights to integer pixels            */

            if ( dist >= 64 )
            {
                dist = ( dist + 16 ) & ~63;
            }
            else
            {
                dist = 64;
            }
        }
        else
        {
            if ( AF_LATIN_HINTS_DO_MONO( hints ))
            {
                /* monochrome horizontal hinting: snap widths to integer pixels */
                /* with a different threshold                                   */

                if ( dist < 64 )
                {
                    dist = 64;
                }
                else
                {
                    dist = ( dist + 32 ) & ~63;
                }
            }
            else
            {
                /* for horizontal anti-aliased hinting, we adopt a more subtle */
                /* approach: we strengthen small stems, round stems whose size */
                /* is between 1 and 2 pixels to an integer, otherwise nothing  */

                if ( dist < 48 )
                {
                    dist = ( dist + 64 ) >> 1;
                }

                else if ( dist < 128 )
                {
                    dist = ( dist + 22 ) & ~63;
                }
                else
                {
                    /* round otherwise to prevent color fringes in LCD mode */
                    dist = ( dist + 32 ) & ~63;
                }
            }
        }
    }

    Done_Width:
    if ( sign )
    {
        dist = -dist;
    }

    return dist;
}


/* align one stem edge relative to the previous stem edge */

static void
af_cjk_align_linked_edge( AF_GlyphHints hints,
                          AF_Dimension dim,
                          AF_Edge base_edge,
                          AF_Edge stem_edge )
{
    FT_Pos dist = stem_edge->opos - base_edge->opos;

    FT_Pos fitted_width = af_cjk_compute_stem_width(
            hints, dim, dist,
            ( AF_Edge_Flags ) base_edge->flags,
            ( AF_Edge_Flags ) stem_edge->flags );


    stem_edge->pos = base_edge->pos + fitted_width;
}


static void
af_cjk_align_serif_edge( AF_GlyphHints hints,
                         AF_Edge base,
                         AF_Edge serif )
{
    FT_UNUSED( hints );

    serif->pos = base->pos + ( serif->opos - base->opos );
}


/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/****                                                                 ****/
/****                    E D G E   H I N T I N G                      ****/
/****                                                                 ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/


#define AF_LIGHT_MODE_MAX_HORZ_GAP    9
#define AF_LIGHT_MODE_MAX_VERT_GAP   15
#define AF_LIGHT_MODE_MAX_DELTA_ABS  14


static FT_Pos
af_hint_normal_stem( AF_GlyphHints hints,
                     AF_Edge edge,
                     AF_Edge edge2,
                     FT_Pos anchor,
                     AF_Dimension dim )
{
    FT_Pos org_len, cur_len, org_center;
    FT_Pos cur_pos1, cur_pos2;
    FT_Pos d_off1, u_off1, d_off2, u_off2, delta;
    FT_Pos offset;
    FT_Pos threshold = 64;


    if ( !AF_LATIN_HINTS_DO_STEM_ADJUST( hints ))
    {
        if (( edge->flags & AF_EDGE_ROUND ) &&
            ( edge2->flags & AF_EDGE_ROUND ))
        {
            if ( dim == AF_DIMENSION_VERT )
            {
                threshold = 64 - AF_LIGHT_MODE_MAX_HORZ_GAP;
            }
            else
            {
                threshold = 64 - AF_LIGHT_MODE_MAX_VERT_GAP;
            }
        }
        else
        {
            if ( dim == AF_DIMENSION_VERT )
            {
                threshold = 64 - AF_LIGHT_MODE_MAX_HORZ_GAP / 3;
            }
            else
            {
                threshold = 64 - AF_LIGHT_MODE_MAX_VERT_GAP / 3;
            }
        }
    }

    org_len = edge2->opos - edge->opos;
    cur_len = af_cjk_compute_stem_width( hints, dim, org_len,
                                         ( AF_Edge_Flags ) edge->flags,
                                         ( AF_Edge_Flags ) edge2->flags );

    org_center = ( edge->opos + edge2->opos ) / 2 + anchor;
    cur_pos1 = org_center - cur_len / 2;
    cur_pos2 = cur_pos1 + cur_len;
    d_off1 = cur_pos1 - FT_PIX_FLOOR( cur_pos1 );
    d_off2 = cur_pos2 - FT_PIX_FLOOR( cur_pos2 );
    u_off1 = 64 - d_off1;
    u_off2 = 64 - d_off2;
    delta = 0;


    if ( d_off1 == 0 || d_off2 == 0 )
    {
        goto Exit;
    }

    if ( cur_len <= threshold )
    {
        if ( d_off2 < cur_len )
        {
            if ( u_off1 <= d_off2 )
            {
                delta = u_off1;
            }
            else
            {
                delta = -d_off2;
            }
        }

        goto Exit;
    }

    if ( threshold < 64 )
    {
        if ( d_off1 >= threshold || u_off1 >= threshold ||
             d_off2 >= threshold || u_off2 >= threshold )
        {
            goto Exit;
        }
    }

    offset = cur_len & 63;

    if ( offset < 32 )
    {
        if ( u_off1 <= offset || d_off2 <= offset )
        {
            goto Exit;
        }
    }
    else
    {
        offset = 64 - threshold;
    }

    d_off1 = threshold - u_off1;
    u_off1 = u_off1 - offset;
    u_off2 = threshold - d_off2;
    d_off2 = d_off2 - offset;

    if ( d_off1 <= u_off1 )
    {
        u_off1 = -d_off1;
    }

    if ( d_off2 <= u_off2 )
    {
        u_off2 = -d_off2;
    }

    if ( FT_ABS( u_off1 ) <= FT_ABS( u_off2 ))
    {
        delta = u_off1;
    }
    else
    {
        delta = u_off2;
    }

    Exit:

#if 1
    if ( !AF_LATIN_HINTS_DO_STEM_ADJUST( hints ))
    {
        if ( delta > AF_LIGHT_MODE_MAX_DELTA_ABS )
        {
            delta = AF_LIGHT_MODE_MAX_DELTA_ABS;
        }
        else if ( delta < -AF_LIGHT_MODE_MAX_DELTA_ABS )
        {
            delta = -AF_LIGHT_MODE_MAX_DELTA_ABS;
        }
    }
#endif

    cur_pos1 += delta;

    if ( edge->opos < edge2->opos )
    {
        edge->pos = cur_pos1;
        edge2->pos = cur_pos1 + cur_len;
    }
    else
    {
        edge->pos = cur_pos1 + cur_len;
        edge2->pos = cur_pos1;
    }

    return delta;
}


static void
af_cjk_hint_edges( AF_GlyphHints hints,
                   AF_Dimension dim )
{
    AF_AxisHints axis = &hints->axis[ dim ];
    AF_Edge edges = axis->edges;
    AF_Edge edge_limit = edges + axis->num_edges;
    FT_PtrDist n_edges;
    AF_Edge edge;
    AF_Edge anchor = 0;
    FT_Pos delta = 0;
    FT_Int skipped = 0;
    FT_Bool has_last_stem = FALSE;
    FT_Pos last_stem_pos = 0;


    /* we begin by aligning all stems relative to the blue zone */
    FT_TRACE5(( "==== cjk hinting %s edges =====\n",
            dim == AF_DIMENSION_HORZ ? "vertical" : "horizontal" ));

    if ( AF_HINTS_DO_BLUES( hints ) )
    {
        for ( edge = edges; edge < edge_limit; edge++ )
        {
            AF_Width blue;
            AF_Edge edge1, edge2;


            if ( edge->flags & AF_EDGE_DONE )
            {
                continue;
            }

            blue = edge->blue_edge;
            edge1 = NULL;
            edge2 = edge->link;

            if ( blue )
            {
                edge1 = edge;
            }
            else if ( edge2 && edge2->blue_edge )
            {
                blue = edge2->blue_edge;
                edge1 = edge2;
                edge2 = edge;
            }

            if ( !edge1 )
            {
                continue;
            }

            FT_TRACE5(( "CJKBLUE: edge %d @%d (opos=%.2f) snapped to (%.2f), "
                        "was (%.2f)\n",
                    edge1 - edges, edge1->fpos, edge1->opos / 64.0, blue->fit / 64.0,
                    edge1->pos / 64.0 ));

            edge1->pos = blue->fit;
            edge1->flags |= AF_EDGE_DONE;

            if ( edge2 && !edge2->blue_edge )
            {
                af_cjk_align_linked_edge( hints, dim, edge1, edge2 );
                edge2->flags |= AF_EDGE_DONE;
            }

            if ( !anchor )
            {
                anchor = edge;
            }
        }
    }

    /* now we align all stem edges. */
    for ( edge = edges; edge < edge_limit; edge++ )
    {
        AF_Edge edge2;


        if ( edge->flags & AF_EDGE_DONE )
        {
            continue;
        }

        /* skip all non-stem edges */
        edge2 = edge->link;
        if ( !edge2 )
        {
            skipped++;
            continue;
        }

        /* Some CJK characters have so many stems that
         * the hinter is likely to merge two adjacent ones.
         * To solve this problem, if either edge of a stem
         * is too close to the previous one, we avoid
         * aligning the two edges, but rather interpolate
         * their locations at the end of this function in
         * order to preserve the space between the stems.
         */
        if ( has_last_stem &&
             ( edge->pos < last_stem_pos + 64 ||
               edge2->pos < last_stem_pos + 64 ))
        {
            skipped++;
            continue;
        }

        /* now align the stem */
        /* this should not happen, but it's better to be safe */
        if ( edge2->blue_edge )
        {
            FT_TRACE5(( "ASSERTION FAILED for edge %d\n", edge2 - edges ));

            af_cjk_align_linked_edge( hints, dim, edge2, edge );
            edge->flags |= AF_EDGE_DONE;
            continue;
        }

        if ( edge2 < edge )
        {
            af_cjk_align_linked_edge( hints, dim, edge2, edge );
            edge->flags |= AF_EDGE_DONE;
            /* We rarely reaches here it seems;
             * usually the two edges belonging
             * to one stem are marked as DONE together
             */
            has_last_stem = TRUE;
            last_stem_pos = edge->pos;
            continue;
        }

        if ( dim != AF_DIMENSION_VERT && !anchor )
        {

#if 0
            if ( fixedpitch )
            {
              AF_Edge     left  = edge;
              AF_Edge     right = edge_limit - 1;
              AF_EdgeRec  left1, left2, right1, right2;
              FT_Pos      target, center1, center2;
              FT_Pos      delta1, delta2, d1, d2;


              while ( right > left && !right->link )
                right--;

              left1  = *left;
              left2  = *left->link;
              right1 = *right->link;
              right2 = *right;

              delta  = ( ( ( hinter->pp2.x + 32 ) & -64 ) - hinter->pp2.x ) / 2;
              target = left->opos + ( right->opos - left->opos ) / 2 + delta - 16;

              delta1  = delta;
              delta1 += af_hint_normal_stem( hints, left, left->link,
                                             delta1, 0 );

              if ( left->link != right )
                af_hint_normal_stem( hints, right->link, right, delta1, 0 );

              center1 = left->pos + ( right->pos - left->pos ) / 2;

              if ( center1 >= target )
                delta2 = delta - 32;
              else
                delta2 = delta + 32;

              delta2 += af_hint_normal_stem( hints, &left1, &left2, delta2, 0 );

              if ( delta1 != delta2 )
              {
                if ( left->link != right )
                  af_hint_normal_stem( hints, &right1, &right2, delta2, 0 );

                center2 = left1.pos + ( right2.pos - left1.pos ) / 2;

                d1 = center1 - target;
                d2 = center2 - target;

                if ( FT_ABS( d2 ) < FT_ABS( d1 ) )
                {
                  left->pos       = left1.pos;
                  left->link->pos = left2.pos;

                  if ( left->link != right )
                  {
                    right->link->pos = right1.pos;
                    right->pos       = right2.pos;
                  }

                  delta1 = delta2;
                }
              }

              delta               = delta1;
              right->link->flags |= AF_EDGE_DONE;
              right->flags       |= AF_EDGE_DONE;
            }
            else

#endif /* 0 */

            delta = af_hint_normal_stem( hints, edge, edge2, 0,
                                         AF_DIMENSION_HORZ );
        }
        else
        {
            af_hint_normal_stem( hints, edge, edge2, delta, dim );
        }

#if 0
        printf( "stem (%d,%d) adjusted (%.1f,%.1f)\n",
                 edge - edges, edge2 - edges,
                 ( edge->pos - edge->opos ) / 64.0,
                 ( edge2->pos - edge2->opos ) / 64.0 );
#endif

        anchor = edge;
        edge->flags |= AF_EDGE_DONE;
        edge2->flags |= AF_EDGE_DONE;
        has_last_stem = TRUE;
        last_stem_pos = edge2->pos;
    }

    /* make sure that lowercase m's maintain their symmetry */

    /* In general, lowercase m's have six vertical edges if they are sans */
    /* serif, or twelve if they are with serifs.  This implementation is  */
    /* based on that assumption, and seems to work very well with most    */
    /* faces.  However, if for a certain face this assumption is not      */
    /* true, the m is just rendered like before.  In addition, any stem   */
    /* correction will only be applied to symmetrical glyphs (even if the */
    /* glyph is not an m), so the potential for unwanted distortion is    */
    /* relatively low.                                                    */

    /* We don't handle horizontal edges since we can't easily assure that */
    /* the third (lowest) stem aligns with the base line; it might end up */
    /* one pixel higher or lower.                                         */

    n_edges = edge_limit - edges;
    if ( dim == AF_DIMENSION_HORZ && ( n_edges == 6 || n_edges == 12 ))
    {
        AF_Edge edge1, edge2, edge3;
        FT_Pos dist1, dist2, span;


        if ( n_edges == 6 )
        {
            edge1 = edges;
            edge2 = edges + 2;
            edge3 = edges + 4;
        }
        else
        {
            edge1 = edges + 1;
            edge2 = edges + 5;
            edge3 = edges + 9;
        }

        dist1 = edge2->opos - edge1->opos;
        dist2 = edge3->opos - edge2->opos;

        span = dist1 - dist2;
        if ( span < 0 )
        {
            span = -span;
        }

        if ( edge1->link == edge1 + 1 &&
             edge2->link == edge2 + 1 &&
             edge3->link == edge3 + 1 && span < 8 )
        {
            delta = edge3->pos - ( 2 * edge2->pos - edge1->pos );
            edge3->pos -= delta;
            if ( edge3->link )
            {
                edge3->link->pos -= delta;
            }

            /* move the serifs along with the stem */
            if ( n_edges == 12 )
            {
                ( edges + 8 )->pos -= delta;
                ( edges + 11 )->pos -= delta;
            }

            edge3->flags |= AF_EDGE_DONE;
            if ( edge3->link )
            {
                edge3->link->flags |= AF_EDGE_DONE;
            }
        }
    }

    if ( !skipped )
    {
        return;
    }

    /*
     *  now hint the remaining edges (serifs and single) in order
     *  to complete our processing
     */
    for ( edge = edges; edge < edge_limit; edge++ )
    {
        if ( edge->flags & AF_EDGE_DONE )
        {
            continue;
        }

        if ( edge->serif )
        {
            af_cjk_align_serif_edge( hints, edge->serif, edge );
            edge->flags |= AF_EDGE_DONE;
            skipped--;
        }
    }

    if ( !skipped )
    {
        return;
    }

    for ( edge = edges; edge < edge_limit; edge++ )
    {
        AF_Edge before, after;


        if ( edge->flags & AF_EDGE_DONE )
        {
            continue;
        }

        before = after = edge;

        while ( --before >= edges )
        {
            if ( before->flags & AF_EDGE_DONE )
            {
                break;
            }
        }

        while ( ++after < edge_limit )
        {
            if ( after->flags & AF_EDGE_DONE )
            {
                break;
            }
        }

        if ( before >= edges || after < edge_limit )
        {
            if ( before < edges )
            {
                af_cjk_align_serif_edge( hints, after, edge );
            }
            else if ( after >= edge_limit )
            {
                af_cjk_align_serif_edge( hints, before, edge );
            }
            else
            {
                if ( after->fpos == before->fpos )
                {
                    edge->pos = before->pos;
                }
                else
                {
                    edge->pos = before->pos +
                                FT_MulDiv( edge->fpos - before->fpos,
                                           after->pos - before->pos,
                                           after->fpos - before->fpos );
                }
            }
        }
    }
}


static void
af_cjk_align_edge_points( AF_GlyphHints hints,
                          AF_Dimension dim )
{
    AF_AxisHints axis = &hints->axis[ dim ];
    AF_Edge edges = axis->edges;
    AF_Edge edge_limit = edges + axis->num_edges;
    AF_Edge edge;
    FT_Bool snapping;


    snapping = FT_BOOL(( dim == AF_DIMENSION_HORZ &&
                         AF_LATIN_HINTS_DO_HORZ_SNAP( hints )) ||
                       ( dim == AF_DIMENSION_VERT &&
                         AF_LATIN_HINTS_DO_VERT_SNAP( hints )));

    for ( edge = edges; edge < edge_limit; edge++ )
    {
        /* move the points of each segment     */
        /* in each edge to the edge's position */
        AF_Segment seg = edge->first;


        if ( snapping )
        {
            do
            {
                AF_Point point = seg->first;


                for ( ;; )
                {
                    if ( dim == AF_DIMENSION_HORZ )
                    {
                        point->x = edge->pos;
                        point->flags |= AF_FLAG_TOUCH_X;
                    }
                    else
                    {
                        point->y = edge->pos;
                        point->flags |= AF_FLAG_TOUCH_Y;
                    }

                    if ( point == seg->last )
                    {
                        break;
                    }

                    point = point->next;
                }

                seg = seg->edge_next;

            }
            while ( seg != edge->first );
        }
        else
        {
            FT_Pos delta = edge->pos - edge->opos;


            do
            {
                AF_Point point = seg->first;


                for ( ;; )
                {
                    if ( dim == AF_DIMENSION_HORZ )
                    {
                        point->x += delta;
                        point->flags |= AF_FLAG_TOUCH_X;
                    }
                    else
                    {
                        point->y += delta;
                        point->flags |= AF_FLAG_TOUCH_Y;
                    }

                    if ( point == seg->last )
                    {
                        break;
                    }

                    point = point->next;
                }

                seg = seg->edge_next;

            }
            while ( seg != edge->first );
        }
    }
}


FT_LOCAL_DEF( FT_Error )
af_cjk_hints_apply( AF_GlyphHints hints,
                    FT_Outline *outline,
                    AF_CJKMetrics metrics )
{
    FT_Error error;
    int dim;

    FT_UNUSED( metrics );


    error = af_glyph_hints_reload( hints, outline );
    if ( error )
    {
        goto Exit;
    }

    /* analyze glyph outline */
    if ( AF_HINTS_DO_HORIZONTAL( hints ))
    {
        error = af_cjk_hints_detect_features( hints, AF_DIMENSION_HORZ );
        if ( error )
        {
            goto Exit;
        }

        af_cjk_hints_compute_blue_edges( hints, metrics, AF_DIMENSION_HORZ );
    }

    if ( AF_HINTS_DO_VERTICAL( hints ))
    {
        error = af_cjk_hints_detect_features( hints, AF_DIMENSION_VERT );
        if ( error )
        {
            goto Exit;
        }

        af_cjk_hints_compute_blue_edges( hints, metrics, AF_DIMENSION_VERT );
    }

    /* grid-fit the outline */
    for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
    {
        if (( dim == AF_DIMENSION_HORZ && AF_HINTS_DO_HORIZONTAL( hints )) ||
            ( dim == AF_DIMENSION_VERT && AF_HINTS_DO_VERTICAL( hints )))
        {

#ifdef AF_CONFIG_OPTION_USE_WARPER
            if ( dim == AF_DIMENSION_HORZ                                  &&
                 metrics->root.scaler.render_mode == FT_RENDER_MODE_NORMAL )
            {
              AF_WarperRec  warper;
              FT_Fixed      scale;
              FT_Pos        delta;


              af_warper_compute( &warper, hints, (AF_Dimension)dim,
                                 &scale, &delta );
              af_glyph_hints_scale_dim( hints, (AF_Dimension)dim,
                                        scale, delta );
              continue;
            }
#endif /* AF_CONFIG_OPTION_USE_WARPER */

            af_cjk_hint_edges( hints, ( AF_Dimension ) dim );
            af_cjk_align_edge_points( hints, ( AF_Dimension ) dim );
            af_glyph_hints_align_strong_points( hints, ( AF_Dimension ) dim );
            af_glyph_hints_align_weak_points( hints, ( AF_Dimension ) dim );
        }
    }

#if 0
    af_glyph_hints_dump_points( hints );
    af_glyph_hints_dump_segments( hints );
    af_glyph_hints_dump_edges( hints );
#endif

    af_glyph_hints_save( hints, outline );

    Exit:
    return error;
}


/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****                C J K   S C R I P T   C L A S S                *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/


/* this corresponds to Unicode 6.0 */

static const AF_Script_UniRangeRec af_cjk_uniranges[] =
        {
                AF_UNIRANGE_REC( 0x2E80UL, 0x2EFFUL ),  /* CJK Radicals Supplement                 */
                AF_UNIRANGE_REC( 0x2F00UL, 0x2FDFUL ),  /* Kangxi Radicals                         */
                AF_UNIRANGE_REC( 0x2FF0UL, 0x2FFFUL ),  /* Ideographic Description Characters      */
                AF_UNIRANGE_REC( 0x3000UL, 0x303FUL ),  /* CJK Symbols and Punctuation             */
                AF_UNIRANGE_REC( 0x3040UL, 0x309FUL ),  /* Hiragana                                */
                AF_UNIRANGE_REC( 0x30A0UL, 0x30FFUL ),  /* Katakana                                */
                AF_UNIRANGE_REC( 0x3100UL, 0x312FUL ),  /* Bopomofo                                */
                AF_UNIRANGE_REC( 0x3130UL, 0x318FUL ),  /* Hangul Compatibility Jamo               */
                AF_UNIRANGE_REC( 0x3190UL, 0x319FUL ),  /* Kanbun                                  */
                AF_UNIRANGE_REC( 0x31A0UL, 0x31BFUL ),  /* Bopomofo Extended                       */
                AF_UNIRANGE_REC( 0x31C0UL, 0x31EFUL ),  /* CJK Strokes                             */
                AF_UNIRANGE_REC( 0x31F0UL, 0x31FFUL ),  /* Katakana Phonetic Extensions            */
                AF_UNIRANGE_REC( 0x3200UL, 0x32FFUL ),  /* Enclosed CJK Letters and Months         */
                AF_UNIRANGE_REC( 0x3300UL, 0x33FFUL ),  /* CJK Compatibility                       */
                AF_UNIRANGE_REC( 0x3400UL, 0x4DBFUL ),  /* CJK Unified Ideographs Extension A      */
                AF_UNIRANGE_REC( 0x4DC0UL, 0x4DFFUL ),  /* Yijing Hexagram Symbols                 */
                AF_UNIRANGE_REC( 0x4E00UL, 0x9FFFUL ),  /* CJK Unified Ideographs                  */
                AF_UNIRANGE_REC( 0xA960UL, 0xA97FUL ),  /* Hangul Jamo Extended-A                  */
                AF_UNIRANGE_REC( 0xAC00UL, 0xD7AFUL ),  /* Hangul Syllables                        */
                AF_UNIRANGE_REC( 0xD7B0UL, 0xD7FFUL ),  /* Hangul Jamo Extended-B                  */
                AF_UNIRANGE_REC( 0xF900UL, 0xFAFFUL ),  /* CJK Compatibility Ideographs            */
                AF_UNIRANGE_REC( 0xFE10UL, 0xFE1FUL ),  /* Vertical forms                          */
                AF_UNIRANGE_REC( 0xFE30UL, 0xFE4FUL ),  /* CJK Compatibility Forms                 */
                AF_UNIRANGE_REC( 0xFF00UL, 0xFFEFUL ),  /* Halfwidth and Fullwidth Forms           */
                AF_UNIRANGE_REC( 0x1B000UL, 0x1B0FFUL ),  /* Kana Supplement                         */
                AF_UNIRANGE_REC( 0x1D300UL, 0x1D35FUL ),  /* Tai Xuan Hing Symbols                   */
                AF_UNIRANGE_REC( 0x1F200UL, 0x1F2FFUL ),  /* Enclosed Ideographic Supplement         */
                AF_UNIRANGE_REC( 0x20000UL, 0x2A6DFUL ),  /* CJK Unified Ideographs Extension B      */
                AF_UNIRANGE_REC( 0x2A700UL, 0x2B73FUL ),  /* CJK Unified Ideographs Extension C      */
                AF_UNIRANGE_REC( 0x2B740UL, 0x2B81FUL ),  /* CJK Unified Ideographs Extension D      */
                AF_UNIRANGE_REC( 0x2F800UL, 0x2FA1FUL ),  /* CJK Compatibility Ideographs Supplement */
                AF_UNIRANGE_REC( 0UL, 0UL )
        };


AF_DEFINE_SCRIPT_CLASS( af_cjk_script_class,
                        AF_SCRIPT_CJK,
                        af_cjk_uniranges,

                        sizeof( AF_CJKMetricsRec ),

                        ( AF_Script_InitMetricsFunc ) af_cjk_metrics_init,
                        ( AF_Script_ScaleMetricsFunc ) af_cjk_metrics_scale,
                        ( AF_Script_DoneMetricsFunc ) NULL,

                        ( AF_Script_InitHintsFunc ) af_cjk_hints_init,
                        ( AF_Script_ApplyHintsFunc ) af_cjk_hints_apply
)

#else /* !AF_CONFIG_OPTION_CJK */

static const AF_Script_UniRangeRec  af_cjk_uniranges[] =
{
  AF_UNIRANGE_REC( 0UL, 0UL )
};


AF_DEFINE_SCRIPT_CLASS( af_cjk_script_class,
  AF_SCRIPT_CJK,
  af_cjk_uniranges,

  sizeof ( AF_CJKMetricsRec ),

  (AF_Script_InitMetricsFunc) NULL,
  (AF_Script_ScaleMetricsFunc)NULL,
  (AF_Script_DoneMetricsFunc) NULL,

  (AF_Script_InitHintsFunc)   NULL,
  (AF_Script_ApplyHintsFunc)  NULL
)

#endif /* !AF_CONFIG_OPTION_CJK */


/* END */
